A typical twin strand continuous casting installation involves the use of two continuous casters located side-by-side and running simultaneously. This arrangement allows a single tundish to be located above the two side-by-side continuous casters, positioned so as to cover about one-half of each continuous caster. The tundish feeds molten metal into both casters.
A typical continuous caster is that shown in French patent 2,534,163, issued Aug. 9, 1985 to Clecim, S. A. In Figure 2 of this French patent is shown a plan view looking down into the continuous casting mold. The Figure shows two long side walls and two short side walls. The short side walls are clamped between the two long side walls. By unclamping the long side walls, the position and angulation of the short side walls can be adjusted. It is common to cool both the short side walls and the large or "long" side walls in order to remove heat from the molten metal. A tundish is located above the mold and has a spout or nozzle delivering molten steel into the space between the long side walls and the short side walls.
Another patent which is representative of the prior art is U.S. Pat. No. 4,523,623, issued to Holleis et al on Jun. 18, 1985.
Conventional continuous caster molds normally include a mechanism at both end walls which includes a threaded drive at the top and another threaded drive at the bottom of the narrow face of the mold. The threaded drives at the top and bottom are interconnected such that when a single shaft is rotated, both of the threaded drives are driven simultaneously. The drives can be uncoupled from one another to allow any desired angling or other adjustment of the end face.
A problem arises in that, for installations of the type described in which two side-by-side continuous casters are fed from a single tundish which overlaps the adjacent end portions of the casters, the tundish tends to be located down closely adjacent the top surfaces of the casters, making it virtually impossible to gain access to the "covered" ends of the casters without moving the tundish. If it is desired to adjust the end walls, then the tundish must first be moved away from the casters, requiring that the whole operation be shut down and that the tundish be emptied. Before it can be used again, the tundish must be relined with refractory material, since the old refractory would be unusable due to being coated with a "skull" of molten metal. In addition yield losses from head and tail crops result when starting and stopping the casting process.
To adjust mold width or taper during casting, present day caster molds or retrofitted caster molds of earlier design are equipped with a drive system for each short side wall. Each drive system is responsible for moving one short side wall or for adjusting its taper.
It is thus clearly desirable, for installations of the kind described, to provide some means by which adjustment of the accessible end wall (the one not covered by the tundish) will automatically cause the non-accessible end wall to be similarly adjusted, and it is an object of one aspect of this invention to provide such means.
It is an object of another aspect of this invention to permit both of the narrow walls of a continuous caster to be adjusted simultaneously while the molding procedure is continuing, thus avoiding the need to shut the system down for adjustment. This advantage is of major importance, because of the very high cost shutting the system down and then starting it up again.